Definition: In this task, you are given an input list A comprising of numbers and alphabets. You need to extract and sort the unique alphabets in the list. The alphabets in the input list will only be in lowercase. Return -1 if there is no alphabet in the input list.
Input: ['9199', 'm', 'c', 'u', 'm', 'q', '6741', 'a', '1111', '8207', '9435', 'k']

a, c, k, m, q, u